The present invention relates generally to the field of communication systems, and more particularly to a system and method operable to facilitate wavelength conversion of a plurality of optical signals.
Conventional wavelength converters typically operate to convert the wavelength of one optical signal from one wavelength to another. Problems associated with, for example, cross-talk between channels and/or polarization sensitivity have generally discouraged utilizing conventional wavelength converters in situations where it is desired to simultaneously convert numerous wavelengths using the same device.
The present invention recognizes a need for a method and apparatus operable to facilitate wavelength conversion of a plurality of optical signals. In accordance with the present invention, a system and method for providing wavelength conversion across a plurality of optical signals reduces or eliminates at least some of the shortcomings associated with other wavelength conversion mechanisms.
In one aspect of the invention, an apparatus operable to convert wavelengths of a plurality of optical signals comprises a coupler operable to receive a pump signal and a plurality of input signals each input signal comprising at least one wavelength different than the wavelengths of others of the plurality of input optical signals. The apparatus further includes an optical medium operable to receive the pump signal and the plurality of input signals from the coupler, wherein the pump signal and each of the plurality of input signals are synchronized to overlap at least partially during at least a part of the time spent traversing the optical medium to facilitate generation of a plurality of converted wavelength signals each comprising a wavelength that is different than the wavelengths of at least some of the plurality of input signals. Various embodiments can result in low cross-talk and/or low polarization sensitivity.
In another aspect of the invention, a method of generating a plurality of converted wavelength signals comprises receiving a plurality of optical input signals each comprising at least one distinct wavelength, and receiving a pump signal comprising a pump wavelength that is either shorter or longer than each of the wavelengths of the plurality of input optical signals. The method further comprises copropagating the plurality of input optical signals and the pump signal over a nonlinear optical medium and generating a plurality of converted wavelength signals based on an interaction between the plurality of input optical signals and the pump signal. Various incarnations of the method can result in multiple wavelength conversion with low cross talk and/or low polarization sensitivity.
In still another aspect of the invention, a system operable to convert a plurality of wavelengths comprises one or more optical transmitters operable to generate alone or in combination a plurality of optical input signals each comprising a wavelength in a first communications band. The system also includes a multiple wavelength converter coupled to the one or more optical transmitters and operable to approximately simultaneously generate, for each of the plurality of optical input signals, a converted wavelength signal comprising a wavelength in a second communications band.
In yet another aspect of the invention, a system operable to convert a plurality of wavelengths to facilitate protection switching comprises an optical medium operable to communicate optical signals comprising wavelengths residing in a first set of wavelengths or a second set of wavelengths, and a multiple wavelength converter coupled to the optical medium. The multiple wavelength converter is operable to receive a plurality of optical signals each comprising a wavelength in the first set of wavelengths and to approximately simultaneously generate, for each of the plurality of optical signals, a converted wavelength signal comprising a wavelength in the second set of wavelengths. The second set of wavelengths comprises a protection path for the first set of wavelengths. The converted wavelength signals can be generated prior to or in response to receiving notice of a fault.
Depending on the specific features implemented, particular embodiments of the present invention may exhibit some, none, or all of the following technical advantages. For example, various embodiments of the invention facilitates converting a plurality of wavelengths, even an entire band of wavelengths, while maintaining low cross-talk and/or maintaining polarization insensitivity. Some embodiments of the invention result in significant cost savings by reducing or eliminating the need for numerous costly filters to deal with harmonics created using other conversion approaches.
Some embodiments of the invention utilize a single polarization beam splitter to communicate with both inputs and outputs of a nonlinear optical medium facilitating wavelength conversion. This approach ensures that signals traversing the medium will experience identical or near identical path lengths and that the polarization of the input signals will be relatively aligned with the polarization of the pump signals.
Particular embodiments of the invention facilitate utilizing existing laser transmitters intended for use with the conventional communication band as transmitters in other communication bands. This aspect of the invention allows for initially generating input optical signals using, for example, C-band transmitters, and then utilizing a multiple wavelength converter to approximately simultaneously convert all of the input signals to wavelengths of another band, such as the S-band or L-band. This approach can save significant resources associated with developing new laser transmitters and can facilitate quick and inexpensive system upgrades.
Other technical advantages are readily apparent to one of skill in the art from the attached figures, description, and claims.